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Message-Id: <1259549968-10369-21-git-send-email-vgoyal@redhat.com>
Date: Sun, 29 Nov 2009 21:59:27 -0500
From: Vivek Goyal <vgoyal@...hat.com>
To: linux-kernel@...r.kernel.org, jens.axboe@...cle.com
Cc: nauman@...gle.com, dpshah@...gle.com, lizf@...fujitsu.com,
ryov@...inux.co.jp, fernando@....ntt.co.jp, s-uchida@...jp.nec.com,
taka@...inux.co.jp, guijianfeng@...fujitsu.com, jmoyer@...hat.com,
righi.andrea@...il.com, m-ikeda@...jp.nec.com, vgoyal@...hat.com,
czoccolo@...il.com, Alan.Brunelle@...com
Subject: [PATCH 20/21] blkio: Wait on sync-noidle queue even if rq_noidle = 1
o rq_noidle() is supposed to tell cfq that do not expect a request after this
one, hence don't idle. But this does not seem to work very well. For example
for direct random readers, rq_noidle = 1 but there is next request coming
after this. Not idling, leads to a group not getting its share even if
group_isolation=1.
o The right solution for this issue is to scan the higher layers and set
right flag (WRITE_SYNC or WRITE_ODIRECT). For the time being, this single
line fix helps. This should not have any significant impact when we are
not using cgroups. I will later figure out IO paths in higher layer and
fix it.
Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
---
block/cfq-iosched.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index e87f0d1..8b528de 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3316,7 +3316,8 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
* only if we processed at least one !rq_noidle request
*/
if (cfqd->serving_type == SYNC_WORKLOAD
- || cfqd->noidle_tree_requires_idle)
+ || cfqd->noidle_tree_requires_idle
+ || cfqq->cfqg->nr_cfqq == 1)
cfq_arm_slice_timer(cfqd);
}
}
--
1.6.2.5
--
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